1. Field of the Invention
The present invention concerns a method of manufacturing, for example, a vehicle seat comprising a skin material, a cushioning pad and a seat frame and, more in particular, it relates to a method of manufacturing a seat using an adhesive capable of forming the seat during a state of assembling also to a seat frame when the cushioning pad and the skin material are integrated by using the adhesive.
2. Description of the Prior Art
In existent vehicle seats in which a skin material and a cushioning pad are bonded by using an adhesive, the skin material and the cushioning pad are disposed between upper and lower dies, and then integrally bonded by heating with the upper and lower dies while a hot melt adhesive in the form of an adhesion film or a solvent type adhesive is present between the skin material and the cushioning pad, and then the integrated skin material and cushioning pad are assembled together with a seat frame in a separate step.
In the step of using the hot melt adhesive, not only is a high heat resistance is required for the skin material and the cushioning pad but also a thermal load is applied to the skin material and the cushioning pad since a higher temperature is necessary for melting the adhesive for bonding. The solvent type adhesive involves a disadvantage in that the cushioning pad and the skin material are bonded during contact since adhesion has already been caused when coating with the adhesive.
For overcoming the foregoing problems in the adhesive, there has been proposed a technique of using a reaction type hot melt adhesive (refer, for example, to Japanese Patent Laid Open Hei 3-68391).
However, also in the technique proposed above, when the skin material and the cushioning pad are bonded, the skin material is disposed in either of the upper or the lower dies, while the cushioning pad is disposed in the other of the dies, and the seat is produced by coating an adhesive an at least one of the opposed surfaces of the cushioning pad and the skin material, followed by heating under pressure and, further, applying cooling on the side of the skin material.
In the technique as described above of placing the skin material and the cushioning pad respectively in the upper and lower dies for bonding them, it is necessary that assembling of the cushioning pad to the die and the assembling of the skin material to the die have to be conducted separately during the step of bonding the skin material and the cushioning pad. Further, when the skin material and the cushioning pad are separately placed in the upper and lower dies, it is necessary that one of the upper and the lower dies be cooled and heated in order to make the molding cycle satisfactory. Heating and cooling of one identical die after bonding the skin material and the cushioning pad makes the molding cycle longer since the identical die is heated and cooled, which decreases the production efficiency. Furthermore, since the cushioning pad and the skin material are heated, cooled and press-bonded by one identical die, lodging or lay down of fluffs in the napped skin material is caused.
Then, for integrally forming the skin material and the cushioning pad together with the seat frame, another separate step of attaching the integrated skin material and cushioning pad to the seat frame is required.